This invention relates generally to the field of analytical spectroscopy and more particularly to methods for the analysis of gases utilizing the generation of ions by photon absorption, involving at least one resonance step, and the measurement of the ionization charge. Where saturation is achieved, the number of ions pairs is numerically equivalent to the number of analyzed species.
One general method known in the art for the determination of a component of a gas is to bring about excited states of an atom of the component by any of several processes and to study the light emitted by these excited states as they return to the ground state. This has numerous problems due to the nature of the states and the light emitted. With most methods of excitation, for example, a number of excited states will be produced at characteristic energy levels and each giving rise to characteristic light emission at low pressure. However, the emitted light has a very complex relationship to the initially excited states at higher pressures since various collisions can alter the distribution of excited species. Also, there are difficulties connected with the detection of light, i.e., the efficiency is relatively low and usually not quantitative.
Thus, there exists a need for an improved method and means for generating selected excited states of a gas to be analyzed and for accomplishing a sensitive and absolute measurement of one or all of the excited states. This need has been accomplished in the present invention in a manner to be described below.